The present invention relates to pneumatic actuators and, more specifically, to a diaphragm assembly for use in pneumatic actuators, in which two or more diaphragms are aligned and nested one on top of another for use in aircraft or other vehicles.
Pneumatic actuators may be found in various applications such as commercial vehicles and aerospace applications. Though pneumatic actuators may be one of the most cost-effective linear actuators, they may be short lived when exposed to high temperatures and pressures. Generally, such low lifespan may be due in part to the wearing of the diaphragm.
A typical pneumatic actuator may include at least a housing, a diaphragm, and a diaphragm support structure. The diaphragm may be made from a flat sheet of fabric, and may be coated on at least one side with an elastomer. In some instances, the diaphragm support structure may have an outer periphery that is generally cylindrical in shape. Thus, the diaphragm may be formed into a so-called xe2x80x9ctop hatxe2x80x9d shape, to conform at least a portion of the diaphragm into a shape that is consistent with the outer periphery of the diaphragm support structure. Because the diaphragm fabric was originally flat, with the fabric weave crossing at right angles, this new shape may cause some of the fabric weave to form a xe2x80x9crainbow-patternxe2x80x9d area when viewed from the diaphragm""s outside.
During the operation of the actuator, the diaphragm may be exposed to numerous pressure cycles. Although actuators and presently used diaphragms are robustly designed and operate safely, in some instances the diaphragm in some actuators may become worn and potentially become inoperative. One particular type of diaphragm failure that may occur following repeated pressure cycles is known as a xe2x80x9ccurtain failure.xe2x80x9d A curtain failure may be recognized as a slit in the diaphragm fabric, and a xe2x80x9cpuckered-outxe2x80x9d region may surround the slit on the diaphragm fabric""s elastomer side.
When the diaphragm fails, the actuator may no longer operate, or not operate correctly. Thus, the actuator may need to be disassembled to effect diaphragm replacement, which can increase overall cost. Hence, there is a need for a diaphragm assembly that may be used in a pneumatic actuator that is less prone to curtain failure and/or is relatively inexpensive to make and/or reduces maintenance and repair costs associated with pneumatic actuators. The present invention addresses one or more of these needs.
The diaphragm assembly provides a diaphragm structure that is relatively low in cost, has an increased diaphragm life, and can reduce overall maintenance and repair costs for the pneumatic actuators into which it is installed.
In one embodiment, and by way of example only, a pneumatic actuator assembly includes a housing and a diaphragm assembly. The housing has an internal chamber and at least a first fluid port in fluid communication with the internal chamber. The diaphragm assembly is located in the internal chamber of the housing to prevent fluid communication between a first portion of the internal chamber and a second portion of the internal chamber. The first portion of the internal chamber is in fluid communication with the fluid port. The diaphragm assembly has a first diaphragm and a second diaphragm. The first and second diaphragms each have an upper surface and a lower surface. The second diaphragm upper surface is positioned adjacent the first diaphragm lower surface. Each of the first and second diaphragms has a fabric portion and has at least a portion of one of its surfaces covered with an elastomeric material. Each fabric portion has at least one fabric pattern, and the fabric patterns of the first and second diaphragms are substantially aligned with one another.
In another exemplary embodiment, a diaphragm assembly includes a first diaphragm and a second diaphragm. The first diaphragm has an outer surface and an inner surface. The second diaphragm has an outer surface and an inner surface, and the second diaphragm outer surface is positioned adjacent the first diaphragm inner surface. Each of the first and second diaphragms is made of a fabric material and has at least a portion of at least one of its surfaces covered with an elastomeric material. The fabric has at least one fabric pattern, and the fabric patterns of the first and second diaphragms are substantially aligned with one another.
In yet another exemplary embodiment, a diaphragm assembly includes a first fabric diaphragm and a second fabric diaphragm. The first fabric diaphragm has a first fabric portion having at least one fabric pattern therein. The second fabric diaphragm has a second fabric portion having at least one fabric pattern therein. Each fabric pattern of the first diaphragm is substantially aligned with each fabric pattern of the second diaphragm.
In still a further exemplary embodiment, in an actuator having a housing assembly and a single diaphragm mounted therein, a method of modifying the actuator includes disassembling at least a portion of the housing assembly. The diaphragm is removed from the housing assembly, and a diaphragm assembly is then installed within the housing assembly. The diaphragm assembly includes at least first and second diaphragms positioned adjacent one another.
In yet still a further embodiment, an actuator including a housing assembly having a first diaphragm mounted therein, the first diaphragm including a fabric portion having at least one fabric pattern, a method of modifying the actuator disassembling at least a portion of the housing assembly. At least a second diaphragm is installed within the housing assembly and positioned adjacent the first diaphragm. The second diaphragm includes a fabric portion having at least one fabric pattern, and the fabric patterns of the first and second diaphragms are substantially aligned with one another.
Other independent features and advantages of the preferred actuator diaphragm assembly will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.